Telephone.



PATENTED MAR. 22, 1904.

M. G. BURT. TELEPHONE.

APPLICATION FILED MAR. 17, 1903.

2' SHEETS-SHEET 1.

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No. 754,968- PATENTED MAR. 22, 1904. M. G. BURT.

TELEPHONE.

APPLIOATION FILED MAR. 17. 1903; N0 MODEL. 2 SHEETS-SHEET 2.

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'UNirnD STATES Patented March 22, 1904.

MARTIN BURT, OF CHICAGO, ILLINOIS.-

TELEPHONE.

SPEGIFICATION forming part of Letters Patent No. 754,968, dated March22, 1904.

Application filed March 1'7, 1903.

To all whom, it may concern:

Be it known that I, MARTIN C. BURT, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Telephones, of which thefollowing is a specification, reference being had therein to theaccompanying drawings.

This invention relates to an improvement in telephones and is embodiedin the construction and arrangement of parts presently to be described,and defined in the claims.

The object of the present invention is largely and primarily to producea telephone, by which term it is to be understood that the same appliesto the receiver or transmitter wherein a multiplicity of magnets can beemployed to vary or modify the magnetic strength or effect on thediaphragm, and in this connection I have shown a telephone-receiverembodying the invention, but have had more particularly inmind theillustration of a transmitter embodying the general principles of theinvention which are largely susceptible of use in other well-known formsof magneto-telephones In the accompanying drawings is shown a phoneembodying the invention; but it is to be understood that variousalterations and changes can be made without departing from theinvention.

Figure 1 is a side elevation showing the switch member and thereceiver-supporting arm, the latter being in a position directly underthe mouthpiece of the transmitter. Fig. 2 is a top plan view showing thereceiver with its arm positioned at right angles to that shown inFig. 1. Fig. 3 is a sectional elevation through the transmitter.

A designates a base; B, the standard of a desk-phone. The standardcarries the forked receiver-arm D. D designates the receiver, and Ethe'transmitter.

The internal construction of the transmitter is conveniently in the formof a series of ring magnets F F F having hollow cores and a portion onlythereof surrounded by the wire wrapping. These cores or magnets areseparated from each other by insulator-blocks f and are carried on aninsulated plate G, se-

Serial No. 148,204. (No model.)

cured to the rear of the transmitter. They are insulated one from theother, so that the energizing of one will not affect the other, theinsulating material being indicated at f. The forward ends of the hollowcores are projected forward and perforated for Venting purposes toprevent undue heating, and the perforated portions are so positioned asto be out of contact with each other, leaving a free space for thecirculation of air therebetween.

Each magnet is coupled up with suitable circuits, (designated at H H HHi) the former being connected with a suitable standard it and thelatter three with a switch plate h and the respective circuits beingconnected, respectively, with the magnets in the transmitter.

J designates a switch-lever pivoted on the standard it and having asector or curved extension at its upper end, on the extreme end of whichis placed the switch-handle. This switch has close contact with the partit and is designed to project successively over the terminals of thewires H, H and H thereby closing the main-line circuit through one ormore of the magnets F F F, thereby securing greater or less magneticforce in the transmitter.

K designates the diaphragm of any approved form of construction,carrying the armatures is k 10 These armatures are conveniently of ringformation to correspond with the magnetic cores, as shown.

The construction of the phone as above described is such that whendesired the operator by the switch, which may be conveniently located,can of his own volition increase or decrease the magnetic strength orextent of magnetic influence on the. diaphragm, a condition which isoften necessary in connection with different conditions of weather orvaria tions in distance.

As above stated, these various features of the telephone described canbe modified without departing from the invention.

. Having thus described the invention, what is claimed as new, anddesired to be secured by Letters Patent, is- I 1. In a telephone, thecombination with a diaphragm carrying armatures, of a series of magnetsfor the armatures, circuits leading to single switch designed to closethe circuits of one or more of the magnets.

3. In a telephone, the combination with a diaphragm, of a series ofmagnets having ho1- low cores arranged one within and insulated fromeach other and the forward ends of which are perforated, armatures onthe diaphragm, circuits leading from the magnets, and a switch for thecircuits.

In testimony whereof I aflix my signature in presence of two witnesses.

MARTIN C. BURT.

WVitnesses:

EDWARD H. YOUNG, J 0s. H. MILANs.

